Pneumatic valve



March 16, 1954 R. A. FISCHER 2,672,085

PNEUMATIC VALVE Filed June 18, 1948 5 :s Sheets-Sheet 1 /NVENTO/?i R/cHA/w A. FISCHER BY H/S ATTORNEYS.

HARRIS, K/acH, Fosrs/e a HARRIS 5) March 16, 1954 FISCHER 2,672,085

PNEUMATIC VALVE Filed June 18, 1948 3 Sheets-Sheet 2 R/CHAA D- A. FISCHER BY HIS ATTORNEYS.

HAP/e16, K/EcH, P057152 & HARE/5 WWW March 16, 1954 R FlSCHER 2,672,085

PNEUMATIC VALVE Filed June 18, 1948 I5 Sheets-Sheet 5 INVENTOR- RICH/9RD A. F/SCHER BK HIS ATTORNEYS. HA RRIS, Knee/ 4. F05 Til? &HH/?/?l$ Patented Mar. 16, 1954 TED ESTATES PAT EN T OFFICE PNEUMATIC VALVE Richard A. .Fischer, Los Angeles, Calm, assignmto The Garrett Corporation, Los =Angeles, Galifi, 1a corporation of California Application June 18, 1948, Serial No.38,845

27 Claims. 2 This invention relates generally to the valve art and particularly to pneumatic -valves tor controlling the how of gases various systems.

While "the invention has "particular utility in connection with pressurized ventilation of aircraft cabins and the like, and is hereinafter shown and described as embodied insuch acon ditioning system, it is to he understood that its utility is not limited thereto.

In the pressurization of aircraft cabins, air is supplied tothe-cahinunderpressure from a-supercharger which is operated continuously during a flight. As is well known to those versed in art, the pressure of air within the cabin must he maintained at .a predetermined value or within a range which provides comfort for the passem gers and crew and safety 'for the aircraft cabin structure. Since annosphefic pressure decreases progressively as the airplane ascends, and increases as the aircraft descends, it is necessary to vary the "pressure of the calcin air soas to effect a differential between the cabin air and that of the ambient atmosphere which will provide comfort "for the passengers and "crew. Thus, cabin pressure may be constant or may he changed at .a gradual pro-selected schedule of increase or decrease "so that the pressure within the cabin will have reached a value substantially that of the ambient atmospheric pressure at the destination of the flight.

The air pressure withlnthe cabin or enclosure is controlled by a valve .cllsposed in an opening in the wall of the enclosure and operative to release an therefrom to maintain the cabin pressure at the required'pressmre, the operation of the valve being responsive to di'fi'erentials between the cabin air pressure and a control chamber pressure. 'Out'fio'vv valves of the diaphragm type are lino'wnt'o those versedin the art. 'Such'valves include valve "plates 'or poppet-s which are adapted to 'Ibe seated and unseated "my movement of a dianhragin, to which they are operatively connected, so as to retain the air within the enclosure "or permit its escapether'efrom in accordance with predetermined requirements. The diaphragm is flexed, to effect movement or the poppets, in response to differentials in pressure on its opposite sides, one side of the diaphragm being exposed to a predetermined fixed. or 'controlledly, varied air pressure while the other side thereof is subfie'cted "to cabin pressure. By this means, the pressure of the air within the enclosure is con trolled so as to maintain *a pie-selected fixed or centrollefily varied cabin pressure.

In order to insure a sensitive -'a'nd posl'tive heretofore been deemed advisable to employ a valve having a panel? the valve :plates or puppets operated by the diaphragm. the arrangement joeing such that the cabin pressure acts against the opposite sides of the two puppets and thus tends to simultaneously open one poppet and close the other poppet. By this provision, movement .of the puppets is not substantially :ailected by the pressure (inferential across :and a substantial balance of forces acting on the ncppets is created. It has been determined, however, that in valves of this clouble ipoppet type one poppet usually movable in a cone of relatively high :pressure while the other poppet is movable in :anerea of lower pressure. This condition tends to aproduce a difference in air new patterns across the faces of the twopoppets, these different patterns changing with the degree of valve opening and thus causing unbalancin'g of the valve system. In order "to overcome this difilculty, epeci'fic'valve contours are required "for particular design requirements as regards diiferentials ibetwee'n enclosure and atmospheric pressures, rates or flow, etc. Moreover, since the two valve plates are connected, and 'thus move in unison, it has been found difficult to manufacture the valve with such precision that both plates or poppets will simultaneously andposi tivelyclose tightlyagamst their seats to prevent leakage of air through the valve.

In an effort to avoid the difliculties mentioned above, valves of a single valve plate or poppe'ttype have been proposed for use in aircraft pressurizlng systems, "such valves being installed in the same "manner as those employing double valve plates or puppets. While a valve of the single poppet type is-more ractical from the manufacturing and servicing standpoint, the disadvantage ofloe'coming 'improperly balanced at some control position, that is, at some 'de'gree of valve opening. That is to say, while the single popp'e't will be "balanced at some particular control position or may be stable between closed and some critical position, furtherincreaseof'flow, as effected by additional opening of the valve may cause instability and flutter. ell-ice the frontal area of the valve poppet is exposed to the directionof the air flowand-thiis same-area ofthe popcontrol or the valve for all conditions, it has pet is the sensing means for controlling the valve, conditions arise where the air flow pattern causes changing pressures on said frontal area of the poppet. thus upsetting or impairing the 'valvecontrol. Again, in "order to overcome the dimculty hast referred to, a specific valve shape is imperaive.

it-t is an object of this invcntion to provide a valve of the single poppet or valve member type for use in air pressurizing systems in which the movable valve member or poppet is free from the deficiencies discussed above and thus maintains a better balance under all conditions of operation. The valve is thus rendered more sensitive in operation and its use results in a more accu rate regulation of the pressure within the cabin or other enclosure being pressurized.

Another object of the invention is to provide a valve, of the character referred to, in which the forces acting on the movable valve member are balanced against each other, one of these forces being that caused by the cabin pressure which is exerted against one side of the valve member and the other being an equal, opposite force caused by the control pressure plus the force of a spring exerted against the opposite side of the valve member. The other remaining forces on the valve member caused by the difference in pressures in the cabin and the ambient atmosphere are exerted equally and oppositely.

Another object is to provide a valve of the type indicated in which the poppet is supported by a diaphragm having a very small portion exposed to ambient atmospheric pressure, this portion being of sufiicient area to provide a force on the movable valve, due to the action or" atmospheric pressure, equal and opposite to the force which is due to atmospheric pressure action, agains the inner area of the movable valve. It is a related object to provide a diaphragm which is of sufficient depth to allow the required opening of the valve for desired quantities of airflow.

Another object is to provide a valve, of the type referred to, in which the movable valve member or poppet is of a frusto-conical shape and provided with a peripheral flange, by which it is secured to the diaphragm, the poppet having a sharp annular end engageable with the valve seat to effectively regulate the flow of air from the cabin to the atmosphere.

Another object is to provide a valve, of the type referred to, which can be installed within the enclosure from which it is to control the efiiux of air or other gaseous fluid.

Another object is to provide a valve of the type specified in which a minimum area of the diaphragm and valve member normal to the direction of flow is disposed in the immediate passage leading past the valve from the cabin to the atmosphere, that is, at or near the zone of greatest air velocity so that turbulence created by the discharging cabin air does not disturb the functioning of the valve.

It is also an object of my invention to provide pressure control means or mechanism for an enclosure or space having a pressure sensitive member operative to position a valve member so as to control flow through an opening of the enclosure, the valve member and a wall or barrier cooperating to provide a pocket adjacent the enclosure opening so shaped that forces applied by fluid pressure in said pocket will not move the valve toward open or closed position.

It is another object of my invention to provide such a pressure control mechanism in which the pressure sensitive means has three areas, one of which is exposed to a pressure in a chamber, the other of which is exposed to pressure in the enclosure, these areas being substantially balanced, and also having a third area exposed to external pressure and being so shaped that external pressure exerts substantially no eifective force in a direction tending to open or close the valve member of the pressure sensitive means.

It is also an object of my invention to pro vide a single poppet valve arrangement of the character herein referred to in which the barrier or central wall is secured to the pressure responsive means by means of a flexible sealing member.

It is a still further object of my invention to provide a flow control mechanism for an enclosure having an opening to the exterior thereof in which the pressure sensitive means includes a flange projecting toward a valve seat surrounding the opening in the enclosure in combination with a wall means cooperating with the flange to form a pocket which is exposed to the exterior of the enclosure through the opening thereof. These elements are combined with a flexible sealing means connecting the wall means and the flange, the flexible sealing means and the flange having opposed surfaces exposed to the pressure in the pocket, the effective areas of the opposed surfaces tending to open and close the valve member being substantially equal to thereby substantially cancel any tendency for the pressure in said pocket to move. the valve arrangement toward open or closed positions.

It is another object of my invention to provide a fluid valve in which there is a barrier means positioned between the pressure sensitive means and the valve seat, this barrier forming a chamber on the side of the pressure sensitive means opposite from the pressure chamber of the assembly, thus protecting the central portion the pressure sensitive means from pressures which may pass inwardly through the opening in the valve seat.

Further objects of the invention will be apparent from the following description and from the drawings which are intended for the purpose of illustration only, and in which:

Fig. 1 is a diagrammatic view of a control system which embodies the present improved pneumatic valve;

Fig. 2 is an enlarged view of the outlet end of the valve shown in Fig. 1;

Fig. 3 is a further enlarged cross-sectional view of the valve taken on line 33 of Fig 2; and

Fig. 4 is a view similar to Fig. 3, showing a modified version of the valve.

. Referring to Fig. 1, there is shown a schematic or diagrammatic representation of a cabin pressure control system of which the present improved pneumatic valve constitutes a component. An enclosure or cabin is indicated generally at iii, which is supplied by air under pressure by a supercharger H, or the like, which may be operated by any suitable source of power, not shown, for maintaining a flow of air into the cabin for purposes of ventilation. The cabin is provided with an outflow opening l2 which is controlled by the present valve, indicated generally at l3, which is capable of directly controlling the cabin pressure by allowing discharge of air from the cabin through the opening into the atmosphere.

Referring to Figs. 1, 2, and 3, one embodiment of the valve [3 comprises a valve body I5 which is in the form of a spider having an annular end plate or ring is adapted to be suitably secured to an inner surface of the wall of the cabin or enclosure 50. I The valve body I5 also has a coaxial annular fiange l'l spaced inwardly from the end plate Hi, the plate and flange being connected by webs or struts it between which, cabin aevaose air --can flew into the central portion or the valve body-and exhaust through a central opening provided between radial webs 2| extending between the end ring plate 1% and a central hubdike portion 21", when thevalve is open.

Surrounding and secured to the periphery of the-flange I? 0*]? the body member l5 is the lower flared end "-2 2 of a cupped casing 23 the walls of which define a control "pressurechamber 2 5. The chamber Eels connected in fluid communication to a regulator device, indicated at 2:5 in Fig. l, by means of aline fl.

Arranged coaxially with the 'valvebody l5 a wall means comprising a disc-like holder or support member 31! having a hub '31 which seats against the central portion 21 oi the end ring lli. bolt 32 passing downwardly th ugh the bore or the member and through a hole in the end plate has a head 33 abutting the upper end of the member. A nut 35 screwed onto the lower proiecting end of the bell; 32 secures the member fixedly in place. Secured to the under side of the holder member 30 by means of an annulus 35 and rivets is the central @ortion of a diaphragm 38, to be later described in detail, which -lorrns part of :a movable valve assembly.

A movable valve member 40, also constituting a component of tlre valve assembly, is disposed within and arranged for axial movement with respect to the valve body ii-E. The valve member includes an annular hangs in and a coaxial irusto-conical extension 42, the lower end of which has its extremity out at an angle to provide, in efiec't, a knil e edge 43 adapted to seat against the upper surface oi the end plate is when the valve member M is moved downwardly so as tocu't oil the outflow of air from the cabin The diaphragm, which may be made from synthetic rubber or other impervious flexible material, extends across the end of the valve member 40 and, is secured thereto by means of an annular clamping element M which is disposed against the upper surface of the diaphragm. Screws 45, passing through aligned holes in the flan e 4 I, the diaphragm "58 and the element 44, receive nuts as which, when tightened, firmly clamp the several parts together. In other cases, rivets or the like may be filnlfi-klyed f-or this purnose. "The diaphragm 38 has a downwardly and laterally extending inner, free, arcua'te convolution "48 between the holder member so and the valve men ll). Thereripheral portion of the diaphragm es extended upwardly and laterally in an outer, free, arcuate convolution 5b. The upper surface the inner convolution "48 is =exposed to control air pressure within the chamber 25 and ambient atmospheric pressure within the 'coniin'esof the irus'to-oo-ni cal extension 42 of the valve member '40. The outer convolution fill is exposed to the control air pressure on one side and on the other side to cabin air pressure. The peripheral portion of the diaphragm 38 may be secured by screws or otherwise elamp'ed between end 22 of the casing 23. Assealing ring 59 is also clam ed thereb'etween so as to prevent new of air between the interior of the cabin and the chamber 2 5.

The sharpened end it of the valve member i 53 which "is lightly compressed between the clamping element 44 and the upper end of casing '23.

The'valve member or flange 40, in combination with the wall or barrier 30, forms apocket which is accessible to the exterior through the valve opening 21. The convolution 48 comprises a flexible means for connecting the movable assembly 30 and 54 to the central member or barrier 30. This movable assembly constitutes a pressure responsive means which is subieoted to chamber pressure on one side and enclosure pressure on the other side as will be explained hereinafter.

The pressure of the air or fluid against the convolution is exerts a force transferred by the outer portion of theiconvolution 4'8 to the pressure responsive means tending to move the same in a direction to open the valve. The frusto-oonic'al flange 2 being of small diameter at its end nearest the valve seat 43 provides an area or shoulder against which pressure of the air or fluid in the pocket bears to produce a force in a direction tending to *close the valve. "These opposed surfaces or areas which are exposed to the fluid in the pocket are such that the forces resulting from the fluidpressure in the pocket are substantially balanced so that the valve will not thereby be moved toward open-or closed positions.

.As explained above, pressure of the air in the chamber .25 is controlled by a regulator device 26 through a line or tube v21 Various types of regulator devices might be employed for this purpose and the present invention is therefore not limited to the use of the :oartioular device shown. The regulator device as, which is herein illustrated by way of example only, will be described briefly as relating to the function of the present improved valve structure 13. The regulating device 2-5 comprises a box or housing 55 defining a chamber 5% in which are disposed two separate pressure controlling systems, namely, an isobaric control system indicated at 51 and a differential control system designated by the reference character '56 in Fig.1, 1

The isobaric r-co ntrol system 5 includes an evaouated bellows so which is connected to operate a needle valve ti which, in turn, controls the flow or air from the chamber 5'6 through a passage 6'2 and into a tube '63 which vents to the atmosphere. The chamber 56 is in communication with the cabin m terior through a restricted orifice M. A spring 65, whose tension may be adjusted by means of a screw 66, is connected by means of a lever 63 to the stem of the needle valve bl and tends "to move the latter to closed position. In practice, the screw it may be operthe oharnber be to the atmosphere by way :of a

setting, air pressure within the control chamber 25 is maintained constant against the upper side of the diaphragm 38 by the action of the isobaric bellows 50 and associated needle valve ii. This pressure, plus the force of the backing spring 53, opposed by cabin pressure acting against the bottom side of the diaphragm, positions the valve 40 so as to control the egress of air from the cabin through the opening to the atmosphere. Any variation of cabin pressure causes an immediate corrective movement of the diaphragm 38 and the directly connected outflow valve 35. The sequence of operation by which this is accom plished is next outlined.

Under high ambient atmospheric pressure conditions, as when the airplane is on the ground near sea level, pressure in the chamber 5% tends to compress the evacuated isobaric bellows iii against the force of the tension spring 65. The isobaric needle valve 6| moves in response to this bellows movement and is in the open position when the bellows is compressed. During pressurized flight, supercharged air in the cabin ll! enters the chamber 56 through the restricted orifice 64 and is allowed to flow out to the atmosphere through the opening 62 of the needle valve 6! to maintain regulating chamber pressure at a constant value somewhat less than cabin pressure. As pressure builds up in the cabin, the pressure differential between the cabin and the regulating chamber increases. This differential moves the diaphragm 38 upwardly, unseating the outflow valve 40 and allowing cabin air to flow to atmosphere through the opening 28. Thus, air is circulated through the cabin but constant presi sure is maintained therewithin.

Referring to Fig. 3 of the drawings, the control pressure within the chamber acts against the top of the diaphragm assembly 38, 44 within an annular area, the width of which is designated by the dimension line A. Since the inner portion of the convolution 48 and the outer portion of the convolution 49 are fixed, only those portions of the convolutions which are adjacent each other need be considered in determining the effective pressure area of the diaphragm assembly, hence the line A extends from the midpoint of the arouate convolution 48 to the midpoint of the armate convolution 49. In determining the total area of the bottom of the diaphragm assembly contacted by the cabin air pressure, this air pressure is considered to act against the lowermost surfaces of the convolution 49, clamping annulus 44, and valve element 4|, including the projected areas of the periphery of the frusto-conical portion 42 and the outer tapered portion of the sharpened edge 43. Since the edge 43 is in vertical alignment with the midpoint of the convolution 48, the bottom area contacted by the cabin air pressure is also represented by the dimension line A. In other words, the areas contacted by the control air pressure and the cabin air pressure are equal. By this provision, the valve member is balanced at any position when the control air pressure plus the spring force is equal to the cabin air pressure. Due to the frusto-conical shape of the extension 42 of the valve member 40, forces on the valve member caused by differences in pressures in the cabin and the ambient atmosphere are exerted equally and oppositely and thus do not disturb the setting of the valve.

When flying in the unpressurized range, as the airplane ascends and atmospheric pressure decreases, the pressure within the chamber 56 also 8 tends to diminish by reason of the open needle valve 6 !--62 which vents to atmosphere through the tube 63. The isobaric bellows 60, which is compressed at sea level, expands as a result of the decrease in regulating chamber pressure and moves the needle valve 6| to restrict the exit of air from the chamber as the airplane climbs. When the isobaric or constant cabin pressure range is reached, this action of the bellows 6| prevents further decrease in pressure within the regulating and control chambers 56 and 25 and maintains the same at a selected constant pressure throughout the isobaric range. With control chamber pressure established at a constant value, any decrease in cabin pressure causes the diaphragm 38 and outflow valve member 40 to move downwardly to restrict the outflow of cabin air until the cabin pressure has returned to its selected value. Thus, for any given setting of the isobaric spring 65, the isobaric control system maintains cabin pressure at a constant value within the limits of the isobaric range of operation.

This discussion has been concerned, up to this point, with operation of the basic regulator 26 at one setting of the isobaric bellows system. The regulator may be adjusted by means of the isobaric changer unit, referred to previously but not shown herein, to regulate the cabin pressure to any value within the isobaric range; and to change the cabin pressure from one value to another at a predetermined rate. When the changer is actuated to adjust the tension spring the pressure sensing action of the isobaric bellows is changed. This causes the regulating and control chambers to assume a new control pressure, which in turn adjusts the cabin pressure to the selected value for the new altitude. The rate at which the tension spring 65 is adjusted by the isobaric changer determines the rate at which cabin pressure is adjusted from one value to another.

As the airplane ascends, the pressure differential between the cabin and atmosphere becomes greater. When the pressure differential reaches a maximum value, for example 4.06 p. s. i., the isobaric bellows 6!] is fully expanded, and the isobaric needle valve Bl-62 is thus closed. At this point, pressurization control is taken over by the differential control system 58. As pre viously pointed out, the interior of the difierential bellows i0 is vented to atmosphere through the tube 63. At the maximum limit of the isobaric range of operation, the pressure differential between the chamber 56 and the interior of the differential bellows H1 is suflicient to contract the bellows and begin opening the directly connected differential needle valve 1|. Since this needle valve is vented to atmosphere, the regulating (and control) chamber pressure will be decreased to the value determined by the setting of the differential tension spring [3. Cabin pressure then acts against the diaphragm 3B and opens the outflow valve 40 the amount required to balance the pressure differential across the diaphragm. This action of the differential control continues throughout the difierential range to regulate cabin pressure to a constant value, for example the 4.06 p. s. i. value, above at mospheric pressure.

It will be apparent from the foregoing that the present improved pneumatic valve is extremely simple in construction and highly efiicient in operation. Since the areas at the opposite sides of the diaphragm assembly which are. subjected. to different air pressures are equal, it follows that the movable valve meme ber: attains perfect balance or stability at. any setting. when thesev pressures become equal in value. Thus, the valve member remains. at rest until a pressure differential erists. between the control chamber 25. and the cabin til. The outer area of the diaphragm 38 which is exposed to. the atmosphere is. of suificient area. to. providea; force. on the movable valve, due; to the action of atmospheric. pressure, and: cppositeto the. force. which is due to atmospheric pressure action against the inner a ea of the movablevalve- This outer areaoi the liaphragm is spacedat a considerable. distance.- from the point. at the air exhausts from. the cabin and consequently the eligeet of. turbulence. upon the. diaphragm is negligible the adjustment or setting of the valve. member All, as. determined by the isobaric or difie-rential. systems; remains unchanged. Ehe. present. valve thus. operates with greater accuracy than other outflowvalves heretoi'ore employed for like purposes; parnote in construction shown is. the

very small or come of the; irustzo- I conical portion 4-2, by reason of which component of the dynamic. force of the. outflawv air in a valve opening direction substantially a euedralf oi thesmall an le.

4; or the drawmga it is the; presentinvention to const at a pneumatic outflow valve 8%. of. the modified constru ion shown therein. this eltern-atlve structure, a. valve body 8.13 of substantially the type the: valve body k5,. 23. em:

ployed. A post Sb supported and extendine ceaxiallvwithin the; valve body 8i... carries: a of clamping discs $2 at. its upper end. The clamping disc-e as receive between themtheeentral portionor a diaphragm he, a nut 86 screwed onto uppcr projecting end; of. the host/2 serving to force thediscs together so as to clamp ae diaphragnatherebetween. The peripheral portion of the diaphragm is clamped between the upper flanged portioniilor thevalve body 8 i the loweeffariged portionoi' a cup shape d control casing 38, by means of; bolts. 88 nuts 8% aseali-ug rang being also intermed be:- tween the to provide airtight connection. interior or the casing as is herein after referred to as tl iecontrol pressure chamher 9%, this chamber vented to the regulating eh-ambentfi through the tube 2*]. A movable'v-alveassembly es includes ave-lamp ing' shell 9% which overlies the discs: es and which has an annular flange at which is disposed against the uppersurface of the diaphragnrflfi. Arr 'ami-ularvalve member 88 has a; peripheral flange S e air-its upper end engaging the lower surface of the-diaphragm 85 directly beneath" the flanges? of the 6 Screws we pass throughaligned holes in flanges ill the diaphragm tanner. nuts-sh! screwed onto the screws-clamp the parts tngether so that'th-e shell t3 valve member'iifi are connected for unitary movement in response to flexing of the diaphragm fleuineit'her direction. w

By thisconstr-ucti'on, an auxiliarylpressure H4 cooperates with. the frusto-conieal part or oi the valve to form a :et accessible. to external. fluid pressures through the valve open-- In this form of invention, however. there provided the; auxiliary chamber its so that in at the; pressure responsive means extends entirely across. the; pressure chamber and has chamber pressure on one side and cabin pressure on the op. ts side A passage Hi l: formedby holes the flange he... the diaphragm 85. and the flange 9.15 commune-ates. between the. chamber Hi3 and the interior of the cabin or enclosure m5 through the openings let.

The lower truism-conical, end, portion iii] of the valve. member S8 has its lower extremity out at an angle to provide, in effect, a sharpened valving edgev ltdwhich, when the valve assembly 95. is moved downwarc'dv, engages a flat annular seat till to. prevent the outward flow of cabin air through, the central opening I I I or" the valve body iii to the atmosphere. A relatively weak spring H2 lightly compressed between the shell at and the upper wall of the casing 88 tends to move the valve assembly to olosedposition.

As shown in Fig. 4, the diaphragm has, a curved convolutionv ild extending between the discs as and the valve member 98 and another curved convolution H5 extending between the valve member and the flange 8,1 or the valve body iii. The. pressure of air within the control pressure chamber 9.2 is applied directly against the entire area of the upper surface of the shell lit and against the convolution I. [5. of the. diaphragm 8d and this pressure is augmented by the force applied by the spring H2. Cabin pressure is applied against the under surface of the convolution H5 of the diaphragm 85 the under surface of the flange $9, of the valve member 98. and the vertically projected area of the, tapered. lower portion 50?. of, the valve member. Ifhis latter pressure is also applied against the under surface of the shell 93., by reason of the passage ltd; through which the cabin air enters the. auxiliary pressure chamber Hi3; It is thus seenv that the control air pressure and the cabin air pressure are applied to equal efiective areas of the respective top and bottom of the valve assembly in all positions of the assembly so that in any flow condi ion the valve assembly is perteotly balanced when the cabin air pressure is equal to the control air pressure plus the force of the spring 1 l2.

The modified valve structure illustrated in Fig. 4 operates in the same manner asthe pneumatic valve shown in Figs. 1 to 3- and like, advantages are obtained through the use of either valve. Whilethe; control and cabin pressures are applied against limited annular areas of the opposite sides of the valve assembly shown in Figs. 1 to 3, these pressures are applied against complete circular areas in the alternative valve.- assembly illustrated in Fig... l; Thus, for operating in the same range of pressures. the modified valveassembly can be made considerably smaller in diameter since the differential pressures act over much greater areas.

I claim as. my invention:

1. A fluid valve for use in. an air pressurizing system. in which air is introduced into an enclosure topressurize the same... comprising; a

11 valve body having an opening therein and a valve seat surrounding said opening; and a valve assembly extending across said valve body and providing at one side a chamber adapted to contain control air under pressure, the other side of the valve assembly being exposed to air external of said chamber, said valve assembly including an air impervious flexible element having its central and peripheral portions fixed and also including a valve member carried by said flexible element and provided with a frusto-conical extension engageable with said seat, said flexible element being adapted to flex in response to differentials in pressure applied against its opposite sides so as to move said valve member toward and away from said seat to regulate the flow of air through said valve body opening, the areas of said valve assembly exposed to said control air pressure and opposing said control air pressure being equal so that said valve assembly is substantially balanced.

2. A fluid valve as defined in claim 1 and including a spring within said chamber and engageable with said valve assembly to augment the force applied against said valve assembly by said control air pressure.

3. A fluid valve as defined in claim 1 and including wide support means for fixedly supporting the central portion of said flexible element so that the flexible area or" said element exposed to said pressures is small and annular.

4. A fluid valve as defined in claim 1 and including wide support means for fixedly supporting the central portion of said flexible element so that the flexible area of said element exposed to said pressures is small and annular, said valve member having an annular flange secured to said annular flexible area.

5. A fluid valve as defined in claim 1 and including wide support means for fixedly supporting the central portion of said flexible element so that the flexible area of said element exposed to said pressures is small and annular, said valve member having an annular flange secured to said annular flexible area, said valve also including a clamping element disposed against said annular flexible area within said chamber in alignment with said annular flange, and fastening means for securing said flange and said clamping element to said annular area, the total area of said flexible element and said clamping element exposed to said control air pressure being equal to the total area of said flexible element and said valve member opposed to said control air pressure.

6. A fluid valve as defined in claim 1 in which said flexible element is provided with an annular convolution of arcuate cross section between said central portion and the point of connection of said valve member, the diameter of the mid-portion of said annular convolution being equal to the diameter of the seat-engaging end of said valve member.

'7. A fluid valve for controlling the pressure in an enclosure having a flow passage to the exterior, comprising: a valve body having a valve opening and having means whereby it may be installed for communication through the flow passage, said valve body having a seat surrounding said opening; a casing attached to said valve body and having a connection to a source of control air pressure; wall means adjacent said valve opening, flexible means secured between said wall means and said casing and cooperating therewith to define a control pressure chamber, said flexible means being adapted to flex in opposite directions in response to differentials in pressure on opposite sides thereof; and a frusto-conical valve member having a free edge cooperable with said seat, said valve member being adjacent said wall means and operatively connected to said flexible means and movable toward and away from said seat to diminish or increase the flow through said opening, said wall means being supported independently of said valve member and being restrained in movement to prevent application of force therefrom through said flexible means to said valve member, the total eflective areas of said flexible means and said valve member exposed to the pressures in said control pressure chamber and to the pressure externally of said control pressure chamber being substantially equal.

8. A fluid valve comprising: a pressure chamber; a valve seat; a pressure responsive element including a valve projecting therefrom toward said seat, one side of said pressure responsive element being exposed to the interior of said pressure chamber, a fixed member supported centrally of said valve; and flexible sealing means connecting said central member and said pressure responsive element.

9. A fluid valve comprising; a pressure chamber; a valve seat; an annular pressure responsive element including a valve projecting therefrom toward said seat; one side of said pressure responsive element being exposed to the interior of said pressure chamber; a member supported within said valve and positioned between said valve seat and said pressure chamber; and flexible sealing means connecting said member and said pressure responsive element.

10. A fluid valve comprising: a pressure chamber; a valve seat; a pressure responsive means having an area subjected to the pressure in said pressure chamber and having a portion comprising a valve operatively connected to said pressure responsive means and pro ecting toward said seat, said pressure responsive means having an annular area outwardly of said valve; barrier means within said valve and between said pressure responsive means and said valve seat, said barrier means cooperating with said pressure responsive means to form a chamber on the side of said pressure responsive means opposite said pressure chamber.

11. A fluid valve comprising: walls defining a pressure chamber having an annular opening: a valve seat; an annular pressure responsive means subjected on one side to chamber pressure through said annular opening and having sealing engagement with said walls forming said annular opening; and an annular valve of smaller external diameter than said annular pressure responsive means projecting from said annular pressure responsive means toward said seat, said valve having a free annular edge engageable with said seat.

12. In a single poppet balanced valve: a valve seat; a central member supported in spaced relation to said seat; a valve member movable toward and from said seat relative to said central memher and cooperating with said central member to form a pocket adjacent to said seat; flexible means forming a seal between said central member and said valve member, said flexible means having an area exposed to the pressure of any fluid in said pocket; and said valve member having an area exposed to the pressure of any fluid in said pocket and being in opposed relationship to the said area of said flexible means.

13. In a, new control tor an enclosurehaving an opening and a valveseat thereabout: a movable valve member comprismg a wall ii'ronr which a. flange extends toward said valve seat, the free: end of said flange being adapted to engage the seatabout said opening; wall means cooperating with. said flange to: form apocliet-exposed to the exterior oi said enclosure said opening thereonsaid valve-mem- Ever being movable: relative tosaidi wall means; one! flexible means: connecting said wallmeans and said flange, said flexible means and said fimge having opposed surfaces exposed to the pressure said pocket so that any force exerted thereagainst produces snbstantial-l'y no effective in a direction. tending to open or close said valve member;

In a new control mechanism for an enclosure having an. oponingand a valve seat thereabout: amovable valve member comprising a wall from a flange extends toward said valve seat, the free end of said flange being adopted to engage the seat about said opening; wil means: cooperating with said flange to form :tpocket exposed to the exterior of said enthrongh said opening thereof, said valve being movable relative to said wall means; and; flexible means connecting said wall means with said mange,- said flexible mean-s and sold flange having opposed surfaces exposed to the fluid entering said: pocket through said opening of said enclosure, the effective areas of. said opposed surfaces tending to open and close said valve member being substantially equal to there by substantially cancel any tendency for the pressure of such fluid to open or close said. valve member;

125.v A fluid valve comprising." a pressure chambet: a valveseat; a pressure responsive element formmg a wall oi said pressure chamber; a valve member supported by said pressure responsive element and projecting therefrom toward said seat; a central member supported within said valve and: positioned between said valve seat and the central portion of saidpressure responsive element; and flexible sealing means connecting said central member and said pressure responsive element.-

16. A fluid valve for controlling the pressure in-an enclosure having a flow passage totheexterior, comprising: a valve body having a valve opening and having means whereby it may be installed for communication through the flow passage, said valve body having a seat surroundl'ng' said opening; a casing attached to said valve bodya-nd having a connection to a source of control air pressure; a flexible element secured between said valve body and said casing and cooperating therewith to define a control pressure chamber; support means for rigidly supporting a central portion of said flexible element so that the effective portion of said element is annular, said efiective portion of said flexible element being adapted tofiexin opposite directionsin response to difierentials in pressure on opposite sides thereof, and a frusto-conical valve member o eratively connected to said annular portion of said flexible element and movable toward and. away from said seat to diminishor increase the flow through said opening, the total effective areas of saidflexible element and said valve member which are cxposedrto the press'urein said control pressurechamber'and to the pressure externally of said control pressure chamber being substantially equal.

17-. A fluid valve for controlling thepressore in an enclosure havin a flow passage to the ex:- t'erior, comprising: a valve body a valve opening and; having means whereby it may be installed for communications through the: new passage; said valve body having a surround;- in-g' said opening: a casing attached to] said valve body and having. a connection to a source of controlv air pressure; a flexible element secured between. said valve body and said casing onoperating therewith to define a pressure chamber support means for rigidly supporting a central portion of said flexible element so that the effective: portion. thereof is. annular. said effective portion ofi said flexible. element being adapted to flex in opposite directions in response: to dillf erentialsin pressure on opposite sides thereof; and anann-ular frosts-conical valve member operatively connected. to said annular portion. of said flexible element, said valve member having an annular seat engaging: portion surrounding said open-iris:r said valve member being movable toward and away from. said seat to or increase the flow through said opening, the total efiective areas of said flexibleelement and said valve member, exposed to the pressures in said control pressure chamber and; to the pressure externally of said pressure clziaarnber being smirstantially equal,

18. A fluid valve for controlling pressure in an enclosure having a flow passage tothe exterior, comprising: a valve body having a valve opening and having means whereby it may he installed for communication. through the now passage, said valve body having aseai; surrounding said opening; a. casing attached to said valve body and having a connection to a source of control air pressure; a flexible element secured between said valve body and said casing and cooperating therewith to define a control pressure chamber; support means for rigidly supporting a central porticniof said flexible element so that the eifective portion thereofi is annular; and an annular frusto-conical valve member socured to one side of said annular portion or said flexible element, said valve including a; rigid clamping element disposed on the opposite side of said flexible element and engaging said ammo lac portion of said flexible element, said flexible element having convolntions between said. support means and said clampmg element and between said clamping element and the point of attachment of said flexible element to said valve body, said convoluted portions being adapted to flex in response to differentials of pressure on opposite sides thereof, said valve member being movable toward and away from said seat to diminish or increase the flow through said opening, the total effective areas of said flexible ele ment and said valve member, exposed to thepressures in said control pressurechamber and; to the DIESSUIE externally" Of said 6011131111 DIESSLIL' chamber, being substantially equal.

19; A fluid valve for controlling the pressure in an enclosure having a flow passage to the exterior', comprising: a valve body having a valve opening and having means whereby it may be installed for communication through the now passage, said valve body having a seat surrounding said opening; a casing attached to said valve body and having a connection to asource of control airpressure; a flexible element secured between said valve body and said. casing and cooperating therewith to define a control pres sure chamber support means for rigidly supporting a central portion of said flexible element so that the effective portion thereof is annular; and an annular frusto-conical valve member secured to one side of said annular portion of said flexible element, said valve also including a rigid clamping element disposed against the opposite side of said annular portion, said valve member being movable toward and away from said seat to diminish or increase flow through said opening, said annular portion of said flexible element having convolutions between said support means and seat clamping element and between said clamping element and the point of attachment of the flexible element with said valve body, said annular portion of said flexible element being adapted to flex in opposite directions in response to differentials of pressure on opposite sides thereto, the annular area of said clamping element and the areas of convolutions of said annular portion between said support means and said clamping element and between said clamping element and the point of attachment of the flexible element with said valve body being exposed to the control air pressure, the area 01 said last-named part of said annular portion of said flexible element and areas of said valve member being exposed to enclosure air pressure, the total area exposed to control air pressure being equal to the total area exposed to enclosure air pressure.

20. A fluid valve for controlling the pressure in an enclosure having a flow passage to the exterior, comprising: a valve body having a valve opening and having means whereby it may be installed for communication through the flow passage, said valve body having a seat surrounding said opening; a casing attached to said valve body and having a connection to a source of "control air pressure; a flexible element secured between said valve body and said casing and cooperating therewith to define a control pressure chamber; a support means for rigidly supporting a central portion of said flexible element so that the effective portion of said flexible element is annular, said effective portion of said flexible element being adapted to flex in opposite directions in respect to diflerentials in pressure "on opposite sides thereof; and a frustoconical valve member, said valve member being annular and secured to one side of said annular portion of said flexible element, said valve also including a rigid, circular, shell disposed at the opposite side of. said flexible element and overlying said support means in spaced relation thereto, said shell having an annular flange secured to said annular portion of said flexible element, said support means and said flexible element and said shell defining between them an auxiliary pressure chamber, said valve member and said flexible element and said shell being provided with a common passage communicating between the interior of the enclosure and said auxiliary pressure chamber so that control air pressure applied against one side of said shell is counteracted by enclosure air pressure applied against the opposite side of said shell, the total area of said shell and said flexible element exposed to control air pressure being equal to the total area of said flexible element, said shell and said valve member exposed to said enclosure air pressure, said valve member being movable toward and away from said seat to diminish or increase the flow through said opening, the total effective areas of said flexible element and said valve member, exposed to the pressures in said control 16' pressure chamber and to the pressure externally of said control pressure chamber, being substantially equal.

21. A fluid valve comprising: a pressure chamber; a valve seat; a pressure responsive element including a valve projecting therefrom toward said seat, one side of said pressure responsive element being exposed to the interior of said pressure chamber; a member supported centrally of said valve; and flexible sealing means extending outwardly of said member and connecting same with said pressure responsive element.

22. A fluid valve comprising: a pressure chamber, a valve seat; a pressure responsive element including a valve projecting therefrom toward said seat; one side of said pressure responsive element being exposed to the interior of said pressure chamber; a member supported within said valve and positioned between said valve seat and said pressure chamber; and flexible sealing means connecting said member and said pressure responsive element.

23. In a flow control mechanism for an aircraft cabin: a chamber; a pressure responsive element having an area on one side exposed to chamber pressure and an area on the other side exposed to cabin pressure; a central member; a flexible wall connecting said central member and said pressure responsive element; and a valve projecting from said pressure responsive element, having a wall with an area in opposing relation to said flexible wall.

24. In a flow control mechanism for an aircraft cabin: a chamber; a pressure responsive element having an area on one side exposed to chamber pressure and an area on the other side exposed to cabin pressure; a central member; flexible means connecting said central member and said pressure responsive element; and a valve projecting from said pressure responsive element, said flexible means and said valve having opposed surfaces exposed to the same air outside said chamber, the effective areas of said opposed surfaces, tending to open and close said valve, being substantially equal to thereby substantially cancel any tendency for the pressure of such air to open or close said valve.

25. A fluid valve comprising: a pressure chamber; a valve seat; a pressure responsive element including a valve projecting therefrom toward said seat, one side of said pressure responsive element being exposed to the interior of said pressure chamber; amember supported centrally of said. valve; and flexible sealing means extending outwardly of said member and peripherally connected with said pressure responsive element.

26. A fluid'valve comprising: a pressure chamber; a valve seat; a pressure responsive element including a valve projecting therefrom toward said seat; one side of said pressure responsive element being exposed to the interior of said pressure chamber; a member fixedly supported within said valve and positioned between said valve seat and said pressure chamber; and flexible sealing means connecting said member and said pressure responsive element.

27. In a pressure control mechanism for controlling the pressure in an enclosure having an opening to the exterior, the combination of: a pressure chamber; pressure responsive means including a movable valve member and a pressure responsive element carrying said valve member, said pressure responsive element having an area exposed to chamber pressure and an opposed area adapted to be exposed to enclosure pressure, said areas being substantially equal; and barrier means having an operable connection with said pressure responsive means so that said pressure responsive means and said connection have opposed areas exposed through the opening in said enclosure to the exterior, said barrier means being supported independently of said valve member and being restrained in movement to prevent application of force therefrom through said operable connection to said pressure responsive means, the last named areas being so formed that the external pressure exerts substantially no effective force in the direction of opening or closing of said valve member.

RICHARD A. FISCHER.

References Cited in the file of this patent Number UNITED STATES PATENTS Name Date Jurs Dec. 10, 1940 .Maxson Dec. 24, 1946 Snedecor Feb. 1'7, 1948 Teague May 4, 1948 Dube Feb. 8, 1949 Widgery et a1 Mar. 1, 1949 Arthur Mar. 1, 1949 Roth et al Oct. 18, 1949 Arthur et al. Nov. 21, 1950 Taylor Dec. 11, 1951 Krueger Mar. 25, 1952 

